May nabuntis na ba dito having sex on their 15th day cycle?

Here's the thing, we had sex on my 15th day cycle at doon na pala niya nilabas. He said, nag masturbate naman daw siya kagabi kaya okay lg daw yun and whatever the result is handa naman kami. Again po, may nabuntis na po ba dito like in this situation? Thank you sa sasagot.